A federal appeals court has rejected a challenge by Massachusetts Attorney General Martha Coakley to the recent relicensing of the Pilgrim Nuclear Power Station in Plymouth.

Coakley contends that nuclear regulators who approved a 20-year extension of the plant's license in May 2012 failed to consider the implications of the 2011 Fukushima Dai-ichi nuclear plant meltdown in Japan after an earthquake and tsunami. Pilgrim's method of storing spent fuel rods is the same one used by the Japanese plant.

Entergy Nuclear owns Pilgrim.

Coakley appealed the decision by the U.S. Nuclear Regulatory Commission to relicense the plant to the U.S. Court of Appeals for the 1st Circuit in Boston, arguing the agency violated its obligations under the National Environmental Policy Act and its own regulations.

Coakley argued that new information from the Japanese nuclear disaster should have been considered in Pilgrim's relicensing.

In its decision released Monday, the court said the NRC acted appropriately in affirming a decision by the Atomic Safety and Licensing Board to deny a request from Coakley's office to hold a hearing on the issue.

The three-judge safety and licensing board is the quasi-judicial arm of the NRC.

Coakley's contention that an environmental review of the plant's operation was inadequate in assessing the impact of the plant's spent fuel pool is covered under a more generic review of nuclear plants and not specific to the relicensing of Pilgrim, according to the appeals court decision.

"The commonwealth confuses the two, and attempts to raise in the petition seeking review of the relicensing issues which both belong in generic rule-making," the three-judge appeals court panel wrote.

The attorney general is reviewing the decision and considering options, according to a statement released by her office.

"Nuclear energy, when done right, can be a valuable part of our energy future," Coakley said. "Our goal throughout this process has been to minimize the public safety and environmental risks for the communities surrounding the Pilgrim plant."

Entergy officials are pleased with the court's decision, company spokeswoman Carol Wightman said.

The decision is the latest in a string of losses for Pilgrim's opponents.

On Jan. 31, the NRC affirmed a finding by the safety and licensing board denying petitions to intervene and requests for a hearing by anti-nuclear activists seeking to challenge the adequacy of safety measures required for the plant.

The safety and licensing board ruled in July that Duxbury-based Pilgrim Watch, which opposes the operation of the plant, could not challenge two orders issued by the NRC in response to the nuclear disaster in Japan.

The orders required that all boiling-water reactors similar to the ones at Pilgrim and Fukushima have reliable venting systems and instrumentation to measure water levels in spent fuel pools.

The 40-year-old Plymouth plant exceeds industry averages for automatic shutdowns and unplanned power changes, according to data provided after two shutdowns in January by federal regulators and nuclear experts. Entergy and NRC officials say the public was never in danger because of the shutdowns.

Cape Downwinders — a group of local anti-nuclear activists — plans to hold a Fukushima Memorial Rally from 1 to 2 p.m. March 9 on the Falmouth Village Green, according to a press release from the group.